steam mains spitting

meticulousmike

i replaced the old steam main vents because they were spitting and leaking.the new ones i bought were from home depot,the only one's they had.well they do the same thing i'm not sure if they are the right size or rating if that matters or if i they make one's with different ratings.they are doing the same thing.what causes this to happen and how do i correct it if i need to?they shouldn't be doing this they will rot the pipe out for sure some day.

Hap_Hazzard

Got pictures? It would make it easier to see what might be happening and how best to address it.

Main vents usually don't have floats, and don't close against water. until they get hot, they remain open. For that reason, it's best to mount them on a 6–10" pipe nipple, or as high above the main as the ceiling will allow. You should probably also get a faster vent than anything Homer has in stock.

Jamie Hall

I honestly don't think Home Depot sells any vents I would use as main vents. Not to disagree with @Hap_Hazzard , but Gorton #2s -- count as main vents (they aren't cheap) and they do have floats and close more reliably against most steam and condensate.

Hap_Hazzard

Jamie Hall said:

Not to disagree with @Hap_Hazzard , but Gorton #2s -- count as main vents (they aren't cheap) and they do have floats and close more reliably against most steam and condensate.

That's right! I forgot about the Gortons. Even the #1, which they call a main vent and can be used as such in sufficient numbers, has a float too.

neilc

I think we need to ask why condensate is getting to the vents in the first place.
What's the Boiler piping like?
a good picture of the boiler and the pipes above, to the ceiling,
And what pressure you're running at,
pigtail clear?
a picture of the presuretrol also,

Long Beach Ed

You have problems with wet steam of high velocity. Chinese Home Depot vents are garbage. A Gorton vent with a float may help, but your problem lies in the configuration or pitch of the piping, not venting.

nicholas bonham-carter

Over-pressure can also raise the water in the wet returns up to the level of the main vents, effectively blocking their operation.--NBC

meticulousmike

i lowered the pressure cut in from 2 psi and i forgot what the differential was at before i changed it i believe 5 down to 1/2 cut in and 1 diff. with the old vents and with the new ones and still they spitted.i had done all the other stuff like clean the pigtail ,glass,ports ,lwco openings,float,etc, i even tried as best as i could to somehow raise the water the highest i could in the system until the vents shot steady streams of water in order to flush the return line to help correct the bouncing below water level to lwco that was shutting off the burners. the original issue was water hammer from flooding the boiler.the owners son was draining it every other day.so with some of the knowledge i had learned here about another boiler from bad experience was that the water was not returning quick enough for the water feed vxt to sense that was enough water in the system.i had replaced the upper brass tube because there were rot holes in it that no one could see.some guy sweated the tube and ferrule to the sight glass valve...i swore this would help cure the bouncing.i did cure the water hammer issue.i also tried to use a little more common sense about what i should know about the vxt and not be confused and overwhelmed by it..i changed the settings from 1 gallon down to lwco and tested to see what that meant and changed the time up a notch or 2...the longer the better in this case..i still have the bounce down and spitting mains but no water hammer..i think i should turn the upper sight glass valve down a bit almost to closing because both of them are wide open.i'm sorry i forgot to post pics in my starter.how stupid of me,i'm always in such a rush.thank you in advance for the help.

ethicalpaul

I agree with @Long Beach Ed

It’s not slow return, it’s that your near boiler piping is out of spec and is throwing boiler water into your main piping. That is my opinion—can’t be sure until pics of the boiler piping.

But no vent nor pressure setting will fix this. You might be able to manage it with water chemistry, waterline height, and/or fire rate

neilc

I think it's time for you to post some pictures,
one good one of the boiler from floor to ceiling, showing all the piping.
and another of the Ptrol showing its settings.
how old is the system?
post a picture of the return pipe as it turns up to return to the boiler.
any drains or plugged tees down there along the floor?
the mains, is there any sagging between hangers, or end to end?
insulation?

meticulousmike

i hope these pics come through and you are able to zoom in if needed.somehow thumbnail images aren't showing in this message only pic links.i told the customer that wrapping the pipes tremendously helps the system.i'm not sure it will help correct these problems though

SteamingatMohawk

How much of the mains going toward the radiators have insulation? To my untrained eye, it looks like the only insulation may be on a return.

Fred

I see a couple issues, the most significant of which is that you have two mains and they return condensate back into a single vertical drop. Both tied together well above the boiler water line. I'm guessing your problem isn't new but has been an on-going issue. When returns are tied together like that, above the boiler water line, it allows steam from one main to cross over into the other. With both your vents right above that, steam from one main will likely close the other prematurely and, with the pressures you were operating at, the pressure probably blew condensate out of the open vent or may have even blew the vents open, spewing water.
- Change that pipe configuration so that both mains (returns) each drop to a level below the boiler water line.
- Keep the Pressuretrol set at .5 Cut-In and "1" Cut-Out
- Get rid of those cheap HD Vents and use either Gorton #2's or Barnes and Jones Big Mouths.
- If at all possible, move your Pressuretrol off of that LWCO (MM #67) and put it in another boiler tapping. When the pigtail is mounted on the McDonnell Miller #67, they will clog at least a couple times per heating season.

SteamingatMohawk

Regarding both returns connected above the water line, I had the same issue and rerouted the returns. I totally agree with @Fred. I also added a drain at the bottom, because there was none. See the before and after pictures.

Hap_Hazzard

In addition to moving the pressuretrol, as Fred suggested, I'd replace the pigtail with a brass one, and make sure the loop is perpendicular to the control so the control stays level. If you can find a brass ¼" pipe union, put that between the pigtail and the pressuretrol so in the future you'll be able to remove it without disconnecting the wires.

ethicalpaul

This dunkirk boiler is the same size and design as mine but with a better header. I think you can get it operating well even though there’s only one side steam supply in use. But everything else will have to be in good shape.

Is that a brass pipe that rotted out?

Steamhead

But it looks like the header is too small- 2" pipe instead of 2-1/2". Can't see for sure but it looks like the steam outlet is bushed down.

meticulousmike

SteamingatMohawk said:

How much of the mains going toward the radiators have insulation? To my untrained eye, it looks like the only insulation may be on a return.

..there's a lot of insulation missing.

meticulousmike

ethicalpaul said:

This dunkirk boiler is the same size and design as mine but with a better header. I think you can get it operating well even though there’s only one side steam supply in use. But everything else will have to be in good shape.



Is that a brass pipe that rotted out?

ethicalpaul said:

This dunkirk boiler is the same size and design as mine but with a better header. I think you can get it operating well even though there’s only one side steam supply in use. But everything else will have to be in good shape.



Is that a brass pipe that rotted out?

yes the brass rotted out.

meticulousmike

SteamingatMohawk said:

Regarding both returns connected above the water line, I had the same issue and rerouted the returns. I totally agree with @Fred. I also added a drain at the bottom, because there was none. See the before and after pictures.

why on earth would you use copper to steel? dissimilar metals always gunk up and clog at their connections.

meticulousmike

Hap_Hazzard said:

In addition to moving the pressuretrol, as Fred suggested, I'd replace the pigtail with a brass one, and make sure the loop is perpendicular to the control so the control stays level. If you can find a brass ¼" pipe union, put that between the pigtail and the pressuretrol so in the future you'll be able to remove it without disconnecting the wires.

either way with a brass one or a steel one the dissimilar metals are bound to gunk up and clog at their connections but the union is a good idea.

KC_Jones

meticulousmike said:

SteamingatMohawk said:

Regarding both returns connected above the water line, I had the same issue and rerouted the returns. I totally agree with @Fred. I also added a drain at the bottom, because there was none. See the before and after pictures.

why on earth would you use copper to steel? dissimilar metals always gunk up and clog at their connections.

Only in the presence of an electrolyte. Those pipes are not submerged so it shouldn't be a big problem. On wet returns copper will stay significantly cleaner than steel, I've had both, there really isn't a comparison. Steel will perpetually have "chocolate", the copper will look like drinking water.

Galvanic corrosion isn't just because 2 metals are in contact, other factors need to be present for it to be an issue. On the pigtails they are above the water line and shouldn't be a problem. The advantage of the brass pigtail is that even if gunk gets into them, it won't tend to "stick" as much so it's easier to clean. A steel pigtail will just rust and gunk up on it's own. Again I've had both, the steel needed yearly cleaning, my brass has been checked yearly, but hasn't needed cleaning for 5 years.

The bottom line for me is, if something isn't maintained anything will be a problem.

meticulousmike

Fred said:

I see a couple issues, the most significant of which is that you have two mains and they return condensate back into a single vertical drop. Both tied together well above the boiler water line. I'm guessing your problem isn't new but has been an on-going issue. When returns are tied together like that, above the boiler water line, it allows steam from one main to cross over into the other. With both your vents right above that, steam from one main will likely close the other prematurely and, with the pressures you were operating at, the pressure probably blew condensate out of the open vent or may have even blew the vents open, spewing water.
- Change that pipe configuration so that both mains (returns) each drop to a level below the boiler water line.
- Keep the Pressuretrol set at .5 Cut-In and "1" Cut-Out
- Get rid of those cheap HD Vents and use either Gorton #2's or Barnes and Jones Big Mouths.
- If at all possible, move your Pressuretrol off of that LWCO (MM #67) and put it in another boiler tapping. When the pigtail is mounted on the McDonnell Miller #67, they will clog at least a couple times per heating season.

Change that pipe configuration so that both mains (returns) each drop to a level below the boiler water line.separate those lines and make 2 right?also aren't they already below the waterline?.so my pressuretrol setting from where it was is right?.if there is another tapping i will move it but perpendicular? if it's a side tap then i will have to find a 90 degree pigtail,correct?if there's one on top (which i don't think there is) i will have to mount it just like it's pictured here on the lwco,correct?..i don't think using a brass or steel pigtail tube would matter much ,either way it's still dissimilar metals..i think i should add a drain at the very bottom of the return so i could drain the gunk out.as for the bouncing below or above waterline should i close the top sight glass valve a bit ?,not fully closed i know but just enough to stop this..thanks for the help.

meticulousmike

Long Beach Ed said:

You have problems with wet steam of high velocity. Chinese Home Depot vents are garbage. A Gorton vent with a float may help, but your problem lies in the configuration or pitch of the piping, not venting.

the pitch i believe is correct.steam outlet close to boiler is high to the joist and then gradually pitches down along the run and the returns are their highest at the end and pitch down as they run towards the boiler.

JUGHNE

The brass/copper tube on the LWCO should only see steam, usually that type of corrosion would come from condensate water. The boiler water must have bounced up to get into the steam tube of the LWCO???
I don't believe you should shut the sight glass valves off, you want to see what the water in the boiler is doing. Throttling down the upper valve to settle down the bounce is not changing anything inside the boiler. Making the sight glass water level steady does not make the problem go away.

Has the boiler ever been skimmed?
Often for this type of side outlets the only place to skim is to have a tee on the discharge outlet which you don't have.
The other side discharge (if there) most likely has a seriously embedded plug in it.
Perhaps you could skim out the port where the rotted LWCO tube was connected. Some creative temp piping to lead the water away and into a bucket might do it.

IIWM, I would relocate the pressure control and new gauge, on an upright pigtail, to the top of the boiler where the existing gauge is now. Install the existing gauge on the tree also as it is required it be somewhere connected. This puts these item at the highest spot away from the sludge of the LWCO.

Hap_Hazzard

meticulousmike said:

either way with a brass one or a steel one the dissimilar metals are bound to gunk up and clog at their connections but the union is a good idea.

Nope. Steel pigtails are much more prone to clogging.

Fred

- @meticulousmike , yes, make two drops, instead of the one that has the second main tied into it. That is definitely tied together above the boiler water line and will allow steam from one main to pass into the other. That's not good.
- Do not close off the top valve on your sight glass. That's not the way to resolve the water bounce. (It will bouce 1/2" to 3/4" during normal operation). Clean and skim the boiler water to stabilize the boiler water.
- Yes, you may need to use an elbow to reposition the Pressuretrol. Just buy a new 90 degree pigtail instead of the straight pigtail that is on there now.
- We prefer brass over metal, not because of the metal differences but because brass tends to have a smoother interior surface and holds less gunk. The steel pigtails have rougher/more porous interior walls that hold gunk.
- Adding a drain on a wet return is always a good idea if it is at a location that will facilitate flushing the returns out.

JUGHNE

And as far as the pictures with the copper drops on the returns; IMO the horizontal "dry return" is still a steam pipe up to the air vents, then it is pretty well a dry return without steam and it seems that copper would be fine.......let us not do the wet/dry/steam discussion again!

But just from removing any old piping on a steamer......the brass and copper will cooperate coming apart much more than steel or iron items.
The only time I have seen corrosion in my area from dissimilar metals of brass and galv iron is on domestic water lines passing fresh water. FWIW

Hap_Hazzard

I think the real problem with steel pigtails is that steel just isn't the best thing to leave standing water in year after year.

meticulousmike

KC_Jones said:

meticulousmike said:

SteamingatMohawk said:

Regarding both returns connected above the water line, I had the same issue and rerouted the returns. I totally agree with @Fred. I also added a drain at the bottom, because there was none. See the before and after pictures.

why on earth would you use copper to steel? dissimilar metals always gunk up and clog at their connections.

Only in the presence of an electrolyte. Those pipes are not submerged so it shouldn't be a big problem. On wet returns copper will stay significantly cleaner than steel, I've had both, there really isn't a comparison. Steel will perpetually have "chocolate", the copper will look like drinking water.

Galvanic corrosion isn't just because 2 metals are in contact, other factors need to be present for it to be an issue. On the pigtails they are above the water line and shouldn't be a problem. The advantage of the brass pigtail is that even if gunk gets into them, it won't tend to "stick" as much so it's easier to clean. A steel pigtail will just rust and gunk up on it's own. Again I've had both, the steel needed yearly cleaning, my brass has been checked yearly, but hasn't needed cleaning for 5 years.

The bottom line for me is, if something isn't maintained anything will be a problem.

KC_Jones said:

meticulousmike said:

SteamingatMohawk said:

Regarding both returns connected above the water line, I had the same issue and rerouted the returns. I totally agree with @Fred. I also added a drain at the bottom, because there was none. See the before and after pictures.

why on earth would you use copper to steel? dissimilar metals always gunk up and clog at their connections.

Only in the presence of an electrolyte. Those pipes are not submerged so it shouldn't be a big problem. On wet returns copper will stay significantly cleaner than steel, I've had both, there really isn't a comparison. Steel will perpetually have "chocolate", the copper will look like drinking water.

Galvanic corrosion isn't just because 2 metals are in contact, other factors need to be present for it to be an issue. On the pigtails they are above the water line and shouldn't be a problem. The advantage of the brass pigtail is that even if gunk gets into them, it won't tend to "stick" as much so it's easier to clean. A steel pigtail will just rust and gunk up on it's own. Again I've had both, the steel needed yearly cleaning, my brass has been checked yearly, but hasn't needed cleaning for 5 years.

The bottom line for me is, if something isn't maintained anything will be a problem.

yes that's true with the steel getting pitted up inside and have the tendency to catch everything and stick.as far as the steel to copper i have seen it in many a faucet hot side and in boilers too.in feeder valves in hot water boilers where the body is steel and the pipes are copper and the lack of movement gunks em' up badly. in steam heat there is air,water and steam until the air is vented out but there's still got to be o2 in the water whether the pipe is filled with water or not,right?

Hap_Hazzard

Not sure to what extent this is relevant, but other elements can cause oxidation. Chlorine is an example.

meticulousmike

JUGHNE said:

The brass/copper tube on the LWCO should only see steam, usually that type of corrosion would come from condensate water. The boiler water must have bounced up to get into the steam tube of the LWCO???
I don't believe you should shut the sight glass valves off, you want to see what the water in the boiler is doing. Throttling down the upper valve to settle down the bounce is not changing anything inside the boiler. Making the sight glass water level steady does not make the problem go away.

Has the boiler ever been skimmed?
Often for this type of side outlets the only place to skim is to have a tee on the discharge outlet which you don't have.
The other side discharge (if there) most likely has a seriously embedded plug in it.
Perhaps you could skim out the port where the rotted LWCO tube was connected. Some creative temp piping to lead the water away and into a bucket might do it.

IIWM, I would relocate the pressure control and new gauge, on an upright pigtail, to the top of the boiler where the existing gauge is now. Install the existing gauge on the tree also as it is required it be somewhere connected. This puts these item at the highest spot away from the sludge of the LWCO.

' Making the sight glass water level steady does not make the problem go away.'..in the case of the water bouncing below the lwco causing it to shutdown does in this situation.

JUGHNE

So do your isolation/service valves on the sight glass also isolate the LWCO from the boiler?
I haven't seen one like that.

meticulousmike

KC_Jones said:

meticulousmike said:

SteamingatMohawk said:

Regarding both returns connected above the water line, I had the same issue and rerouted the returns. I totally agree with @Fred. I also added a drain at the bottom, because there was none. See the before and after pictures.

why on earth would you use copper to steel? dissimilar metals always gunk up and clog at their connections.

Only in the presence of an electrolyte. Those pipes are not submerged so it shouldn't be a big problem. On wet returns copper will stay significantly cleaner than steel, I've had both, there really isn't a comparison. Steel will perpetually have "chocolate", the copper will look like drinking water.

Galvanic corrosion isn't just because 2 metals are in contact, other factors need to be present for it to be an issue. On the pigtails they are above the water line and shouldn't be a problem. The advantage of the brass pigtail is that even if gunk gets into them, it won't tend to "stick" as much so it's easier to clean. A steel pigtail will just rust and gunk up on it's own. Again I've had both, the steel needed yearly cleaning, my brass has been checked yearly, but hasn't needed cleaning for 5 years.

The bottom line for me is, if something isn't maintained anything will be a problem.

i rest my case here with words from the man himself dan .This is an excerpt from Dan Holohan's popular book We Got Steam Heat!: A Homeowner's Guide to Peaceful Coexistence.i knew there was more than one reason..it was on the tip of my tongue...:Copper expands much more than steel, and that’s an important consideration, seeing as there’s so much twisting and turning going on in these systems. That’s what those odd pipe angles are all about. They allow the pipe to expand and contract and twist without upsetting the pitch needed for proper condensate drainage. If the pitch isn’t right, you’ll wind up with noisy water hammer and uneven heat (and high fuel bills).,Another problem with copper is that it leaches out and into the boiler as time goes by. This can cause dielectric corrosion within the boiler, and that shortens the boiler’s life. You wind up buying another boiler.,And this problem with expansion and contraction is especially critical within the near-boiler piping.

Hap_Hazzard

Copper "leaches" much less than steel or cast iron. Copper is much higher on the galvanic scale, that is, more "noble" than steel or iron. Another way to think of it is to remember that copper (Cu) is in the same period as gold (Au) which is the second most corrsion-resistant metal on earth.

Galvanic corrosion is an issue where the two metals are in contact in the presence of an electrolyte, but if the pipe joints are properly taped with PTFE, they are separated by a very effective dielectric, so little to no corrosion should occur.

Regarding the expansion coefficient, this isn't a problem in return piping or pigtails, as only one end of the pipe or pigtail is connected to the boiler, leaving the other end free to move, and it doesn't move that much. Comparing the α of steel (~11.65) to that of copper or brass (~17.5), the difference is significant, but remember that α is in terms of 10⁻⁶ in/in °F, so the actual change in length of a copper pipe, from 70°F to 212°F, works out to about 0.0298" per foot. It just doesn't make a whole lot of difference unless the two materials are connected at both ends.